Alter (crater)
Encyclopedia
Alter is a lunar
impact crater
that is located in the northern hemisphere
on the far side of the Moon
. It lies to the southwest of the larger crater Robertson
, and to the east of Ohm
.
The outer rim of Alter has been degraded by subsequent erosion, most notably at the northern and southern extremes. There is a small crater lying across the south-southeast rim. A cleft runs across the floor from the southern rim toward the north-northeast. Ray
material cross the crater floor from the east, forming a pair of faint bands.
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
impact crater
Impact crater
In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...
that is located in the northern hemisphere
Sphere
A sphere is a perfectly round geometrical object in three-dimensional space, such as the shape of a round ball. Like a circle in two dimensions, a perfect sphere is completely symmetrical around its center, with all points on the surface lying the same distance r from the center point...
on the far side of the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
. It lies to the southwest of the larger crater Robertson
Robertson (crater)
Robertson is an important lunar impact crater that is located on the far side of the Moon, just beyond the western limb. It lies just to the south of Berkner, a formation with a comparable size but more eroded features. Just to the east is Helberg, and to the southwest is Alter.The inner wall of...
, and to the east of Ohm
Ohm (crater)
Ohm is a lunar impact crater that is located on the far side of the Moon. It lies to the south of the crater Comrie, and the satellite crater Comrie K is attached to Ohm's northeastern rim...
.
The outer rim of Alter has been degraded by subsequent erosion, most notably at the northern and southern extremes. There is a small crater lying across the south-southeast rim. A cleft runs across the floor from the southern rim toward the north-northeast. Ray
Ray system
A ray system comprises radial streaks of fine ejecta thrown out during the formation of an impact crater, looking a bit like many thin spokes coming from the hub of a wheel. The rays can extend for lengths up to several times the diameter of their originating crater, and are often accompanied by...
material cross the crater floor from the east, forming a pair of faint bands.
Satellite craters
By convention these features are identified on lunar maps by placing the letter on the side of the crater mid-point that is closest to Alter.| Alter | Latitude | Longitude | Diameter |
|---|---|---|---|
| K | 16.3° N | 106.0° W | 22 km |
| W | 20.4° N | 109.2° W | 52 km |